Air to air heat exchangers are commonly used to cool a heated stream of process air using ambient air. A particular example of such heat exchangers can be found in so-called charge air coolers for internal combustion engine systems. In such systems, the air being delivered to the combustion chambers is compressed using the otherwise wasted enthalpy remaining in the exhaust stream. The associated heating of the process air by this compression is undesirable, as it leads to increased emission levels of regulated pollutants, as well as a reduced engine thermal efficiency caused by the relatively low density of the heated air. It is therefore desirable for the compressed process air to be cooled prior to delivery of the air to the combustion chambers.
In some conventional constructions of air to air heat exchangers for charge air cooling, the heated air is cooled by a flow of ambient air that is directed in cross-flow orientation to the heated air. In one particular style of such a heat exchanger, commonly referred to as a bar-plate style, flat plates and bars are used to interleave alternating flow channels for the two fluids in order to transfer heat between them. Such heat exchangers are known to be susceptible to thermal fatigue, due to the stresses imparted on the heat exchanger by the high, fluctuating temperatures of the heated air.